Semi-free bending-stamping composite process for thin-wall part

Abstract

The invention discloses a semi-free bending-stamping composite process for a thin-walled workpiece, which is realized by the following steps of: firstly, carrying out preliminary bending forming on a thin-walled micro-channel flat tube by utilizing a semi-free bending process and combining a rubber pressing block, a bending block and a rubber roller; then, a stamping process is adopted, the corrugation is precisely shaped through die assembly of a left stamping block, a right stamping block and a bending block, and the accuracy of the corrugation size is ensured; and finally, preparation is made for production of the next corrugation through a rotary resetting step. According to the technology, the continuous waveform production process is innovatively decomposed into single waveforms for one-by-one manufacturing, and the problems that in the plastic deformation process, thin-wall materials are prone to distortion, cracking and the like are effectively solved. The flexible degree of the technological process is high, and distortion and breakage can be effectively avoided; a springback compensation surface of the stamping block is designed, so that the influence of springback on the forming precision is reduced; the process is simple in procedure and high in production efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of continuous bending and stamping shaping analysis of thin-walled parts, and particularly relates to a semi-free bending-stamping composite process for thin-walled parts. Background Art

[0002] With the increasing requirements for energy conservation and emission reduction, the fields of aerospace, automotive, and construction are actively exploring lightweight designs. Due to its special corrugated shape, thin-walled corrugated plates can provide good structural performance while reducing the amount of material used. This makes it an important and efficient choice in the manufacturing field.

[0003] Microchannel flat tubes are favored in heat dissipation devices due to their large surface area ratio and are widely used in the heat exchange systems of household appliance condensers, automotive battery packs, and aero-engine heat exchange systems. Numerous studies have shown that corrugated microchannels have higher heat transfer efficiency compared to straight microchannels. Currently, the existing corrugated microchannels are mainly obtained through casting or machining, so the overall structure is relatively bulky and the fit with the heat dissipation components is poor. In sharp contrast, thin-walled microchannel corrugated flat tubes show significant advantages in terms of lightweight and flexibility. However, the lack of an effective corrugation forming process for thin-walled microchannel corrugated flat tubes restricts their application prospects in a wider industrial field.

[0004] Currently, stamping remains the mainstream production method for thin-walled microchannel corrugated flat tubes and thin-walled corrugated plates. However, serious cross-section distortion or damage and rupture often occur during stamping. Some studies use multi-step stamping or segmented stamping. But this processing method still has problems such as poor material fluidity, poor defect prevention, low production efficiency, and difficulty in maintaining stable corrugation size accuracy in the forming of thin-walled corrugated parts. Therefore, in view of the deficiencies of the existing technology, a new forming process for thin-walled corrugated flat tubes (thin-walled corrugated plates) is urgently needed. Summary of the Invention

[0005] In view of the above deficiencies of the existing technology, the present invention provides a semi-free bending-stamping composite process for thin-walled parts. When producing thin-walled microchannel corrugated flat tubes or thin-walled corrugated plates, continuous waveforms are produced one by one as single waveforms. The fluidity of the material is improved through the semi-free bending process, the cross-section distortion and damage degree are reduced, and corrugations with a narrower wave pitch and a larger wave height can be formed. Moreover, through the stamping process, the precise forming of the corrugation size is achieved.

[0006] A semi-free bending-stamping composite process for thin-walled parts includes the following steps: semi-free bending forming, stamping forming, and rotational resetting;

[0007] Step 1: In the semi-free bending forming step, the thin-walled part is transported to the bending block by a conveying mechanism and semi-freely bent and formed along the bending block;

[0008] Step 2: In the stamping step, the left stamping block and the right stamping block stamp the free-bending thin-walled part in the step;

[0009] Step 3: In the rotation and resetting step, the thin-walled part after the stamping in step 2 is rotated by a certain angle after removing the left stamping block and the right stamping block;

[0010] Repeat steps 1 to 3 to create new waves.

[0011] In the above solution, in step 1, the thin-walled part is pressed tightly against the bending block by the rubber pressing block.

[0012] In the above scheme, in step 2, the rubber pressing block is disengaged, and the left punching block and the right punching block are molded together to form a semi-corrugated surface for stamping.

[0013] In the above scheme, in step three, the half-wave corrugation is positioned and supported by a positioner, wherein the positioner is a rod-shaped structure with several positioning rods evenly distributed on the positioner, and the positioning rods are used to position the half-wave corrugation.

[0014] In the above scheme, step three specifically includes the following steps:

[0015] (1) The left punching block and the right punching block are moved away;

[0016] (2) The positioner drives the rubber pressure block and the positioning rod to return to the base plane together with the bending block;

[0017] (3) The positioner rotates 180 degrees in the opposite direction around the central axis;

[0018] (4) The left punch block and the right punch block move back to the base plane;

[0019] (5) The multiple sets of rubber rollers move horizontally in the opposite direction of the clamping to break away from the clamping state; at this point, the left punching block, the right punching block, the bending block, the positioner and the multiple sets of rubber rollers all leave space for the rotational movement of the thin-walled part;

[0020] (6) The rotating table clamps the thin-walled part with an elastic clamping piece and rotates 180° along the central axis of the feeding direction. Then, the rotating table releases the clamping of the thin-walled plate;

[0021] (7) Translational reset of the positioning block and bending block;

[0022] (8) The positioner relies on the positioning element to fine-tune the position of the thin-walled part to ensure precise alignment;

[0023] (9) The rubber pressing block is reset to press the thin-walled part tightly against the bending block;

[0024] (10) Multiple sets of rubber rollers are reset to restore the clamping contact with thin-walled parts.

[0025] In the above solution, the working surfaces of the left stamping block and the right stamping block are springback compensation surfaces.

[0026] In the above solution, the rubber pressing block and the positioning element can move relative to the positioner.

[0027] In the above solution, the bending block is circular, elliptical, sinusoidal or helical in shape.

[0028] In the above solution, the side of the rubber pressing block that fits the thin-walled plate is the elastic surface, and the other side is the rigid surface.

[0029] In the above solution, the thin-walled part is a thin-walled plate or a thin-walled microchannel flat tube.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] (1) This process produces continuous waveforms as single waveforms one by one, belonging to a flexible incremental forming process, thereby reducing the tension state of material flow during plastic deformation. It can effectively overcome the distortion and cracking problems of thin-walled corrugated flat tubes or thin-walled corrugated plates, and is particularly suitable for solving the problem that thin-walled materials are prone to cracking due to excessive local plastic deformation.

[0032] (2) This process has simple procedures, relatively low complexity in overall process control, high automation, strong continuous operation ability, and high production efficiency.

[0033] (3) This process has a high degree of flexibility. The shape of the bending block can be designed as circular, elliptical, sinusoidal, helical, etc. to meet the waveform shape requirements of different thin-walled flat tubes or thin-walled plates.

[0034] (4) This process can design the working surfaces of the left stamping block and the right stamping block as springback compensation surfaces to reduce the forming accuracy problems caused by springback. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the features, objectives and advantages of the present invention, the following will briefly introduce the specific implementation manners and the drawings required for the present invention.

[0036] Figure 1 is a schematic structural diagram and a motion schematic diagram of the processing device in the present invention;

[0037] Figure 2 is a flowchart of the semi-free bending-stamping composite process in the present invention;

[0038] Figure 3 is a forming diagram obtained according to the process of the present invention;

[0039] Figure 4 is a forming schematic diagram obtained by the traditional stamping process.

[0040] The reference numerals are as follows:

[0041] 1-rotating table, 2-elastic clamping plate, 3-multiple sets of rubber rollers, 4-thin-walled parts, 5-left punching block, 6-right punching block, 7-rubber pressing block, 8-locator, 9-positioning element, 10-bending block. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the present invention more accurate and clear, the present invention is further described in detail below in conjunction with the embodiments and drawings. It should be noted that the specific embodiments described herein are only used to explain the present invention in detail and are not used to limit the invention. Based on the described embodiments, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention.

[0043] A semi-free bending-stamping composite process for thin-walled parts comprises the following steps:

[0044] Step 1: Semi-free bending

[0045] In this step, the thin-walled microchannel flat tube or thin-walled plate is pressed on the bending block 10 by the rubber pressing block 7, and the initial bending position is simply positioned by the positioner 8; multiple groups of rubber rollers 3 clamp the thin-walled microchannel flat tube or thin-walled plate, and the thin-walled microchannel flat tube or thin-walled plate is moved forward through the skew rotation of each group of rubber rollers; at the same time, the rubber pressing block 7 and the positioner 8 position and support the thin-walled microchannel flat tube or thin-walled plate, and rotate around the bending block 10 to form an initial corrugated shape. In this step, the thin-walled microchannel flat tube or thin-walled plate is less constrained by the mold than the traditional bending forming, and the severity of material deformation is relatively low, so it is also called semi-free bending forming;

[0046] Step 2: Stamping

[0047] In this step, the multiple sets of rubber rollers 3 stop rotating, and the rubber pressing block 7 is disengaged and adsorbed on the positioner 8. The left punching block 5 and the right punching block 6 move horizontally and mold with the left half wave surface and the right half wave surface of the bending block 10 to accurately shape the corrugation of the thin-walled microchannel flat tube or thin-walled plate, so that a single corrugation is formed. In this step, the action surface of the left punching block 5 and the right punching block 6 can be designed as a rebound compensation surface to reduce the forming accuracy problem caused by the rebound.

[0048] Step 3: Rotate to reset

[0049] Before a new single corrugation is formed, the thin-walled microchannel flat tube or thin-walled plate needs to be rotated and reset to restore the initial bending state. The process includes the following steps:

[0050] (11) The left punch block 5 and the right punch block 6 move horizontally out of the mold clamping state;

[0051] (12) The positioner 8 carries the rubber pressure block 7 and the positioning element and retracts into the base plane together with the bending block 10;

[0052] (13) The positioner 8 rotates 180 degrees in the opposite direction around the central axis, wherein the bending block 10 can rotate with it, which is selected according to the shape of the bending block;

[0053] (14) The left punch block 5 and the right punch block 6 move back to the base plane;

[0054] (15) The multiple sets of rubber rollers move horizontally in the opposite direction of the clamping to break away from the clamping state. At this point, the left punching block 5, the right punching block 6, the bending block 10, the positioner 8 and the multiple sets of rubber rollers 3 all leave space for the rotation of the thin-walled microchannel flat tube or the thin-walled plate;

[0055] (16) The rotating table clamps the thin-walled microchannel flat tube or thin-walled plate with an elastic clamping piece, and rotates 180° along the central axis of the feeding direction, and then releases the clamping of the thin-walled microchannel flat tube or thin-walled plate by the rotating table;

[0056] (17) The positioning block and the bending block 10 are reset in translation;

[0057] (18) The positioner relies on the positioning element to fine-tune the position of the thin-wall microchannel flat tube or thin-wall plate to ensure precise alignment;

[0058] (19) The rubber pressing block 7 is reset to press the thin-walled microchannel flat tube or thin-walled plate onto the bending block;

[0059] (20) multiple sets of rubber rollers are reset to restore the clamping contact with the thin-wall microchannel flat tube or thin-wall plate;

[0060] Repeat steps 1 to 3 until new waves are formed.

[0061] Preferably, thin-walled microchannel flat tubes or thin-walled plates carrying filling media are the best preparation materials.

[0062] Preferably, under the support of the elastic clamping sheet, the thin-walled microchannel flat tube or thin-walled plate can rotate along with the rotating table, that is, it has a high degree of freedom.

[0063] Preferably, in the process, the bending block 10 can be designed to be circular, elliptical, sinusoidal, spiral or other shapes according to requirements, and can also move forward and backward, so as to facilitate cooperation with other molds.

[0064] Preferably, in the process, the positioner carrying the rubber pressing block 7 and the positioning element can move left and right, can rotate around the bending block, has a high degree of freedom, is convenient for cooperating with other molds, and at the same time avoids affecting the operation of other molds.

[0065] Preferably, in the process, the working surfaces of the left stamping block 5 and the right stamping block 6 can be designed as springback compensation surfaces, and at the same time, the stamping blocks can achieve synchronous and asynchronous movements, and can also move left and right, up and down, forward and backward, so as to meet different working requirements.

[0066] Preferably, in the process, after each half-wave bending forming is completed, the left stamping block 5, the right stamping block 6, the bending block 10, the positioner 8 and multiple groups of rubber rollers leave space for the rotational movement of the thin-walled microchannel flat tube or thin-walled plate, avoiding interference and preparing for the next half-wave bending forming.

[0067] The machine tool or moving workbench used supports motion control in the X, Y, Z, A, and C directions and is provided with a rotating table.

[0068] During the process, according to the actual processing situation, the number of groups, pressure, rotational speed of the rubber rollers, the pressure of the rubber pressing block, the rotational speed of the bending block, the clamping force of the stamping block, the sequence of clamping, the fine-tuning position of the positioning element, and the rotational speed of the rotating table and other parameters can be adjusted in a timely manner.

[0069] Through the above implementation scheme, combined with the multi-axis motion freedom of the machine tool, the corrugation forming process of the thin-walled microchannel flat tube (thin-walled plate) can be completed efficiently and accurately.

[0070] Combined with the attached Figure 3 、 4 shown and Table 1, the schematic diagram of the half-wave corrugation obtained by the process of the present invention is Figure 4 the forming schematic diagram obtained by the traditional stamping process. In the finite element simulation, compared with the traditional stamping process, the average bending radius deviation rate, the maximum cross-section collapse rate, the average wall thickness change rate, and the maximum wall thickness thinning rate of this process are all better than those of the traditional stamping process, while the average cross-section collapse rate and the maximum value of the damage factor of the two processes are not much different.

[0071] Table 1 Bending comparison parameters obtained by the process of the present invention and the traditional stamping process

[0072]

[0073] The above is an illustrative example of the present invention through examples and does not limit the scope of implementation of the present invention. All equal changes and improvements made through the present invention should still fall within the patent coverage scope of the present invention.

Claims

1. A semi-free bending-stamping composite process for thin-walled parts, characterized in that: The method comprises the following steps: semi-free bending forming, stamping forming and rotation resetting; Step 1: In the semi-free bending forming step, the thin-walled part is conveyed to the bending block by the conveying mechanism and semi-free bent along the bending block; Step 2: In the stamping step, the left stamping block and the right stamping block stamp the free-bending thin-walled part in the step; Step 3: In the rotation and resetting step, the thin-walled part after the stamping in step 2 is rotated by a certain angle after removing the left stamping block and the right stamping block; Repeat steps 1 to 3 to create new waves.

2. The semi-free bending-stamping composite process of thin-walled parts according to claim 1 is characterized in that: In step 1, the thin-walled part is pressed tightly against the bending block by the rubber pressing block.

3. The semi-free bending-stamping composite process of thin-walled parts according to claim 1 is characterized in that: In step 2, the rubber pressing block is disengaged, and the left punching block and the right punching block are molded together to form a semi-corrugated surface for stamping.

4. The semi-free bending-stamping composite process of thin-walled parts according to claim 1, characterized in that: In step three, the half-wave corrugation is positioned and supported by a positioner, wherein the positioner is a rod-shaped structure with several positioning rods evenly distributed on the positioner, and the positioning rods are used to position the half-wave corrugation.

5. The semi-free bending-stamping composite process of thin-walled parts according to claim 4 is characterized in that: Step 3 specifically includes the following steps: (1) The left punching block and the right punching block are moved away; (2) The positioner drives the rubber pressure block and the positioning rod to return to the base plane together with the bending block; (3) The positioner rotates 180 degrees in the opposite direction around the central axis; (4) The left punch block and the right punch block move back to the base plane; (5) The multiple sets of rubber rollers move horizontally in the opposite direction of the clamping to break away from the clamping state; at this point, the left punching block, the right punching block, the bending block, the positioner and the multiple sets of rubber rollers all leave space for the rotational movement of the thin-walled part; (6) The rotating table uses an elastic clamping plate to clamp the thin-walled part and rotates 180° along the central axis of the feeding direction. Then, the rotating table releases the clamping of the thin-walled plate; (7) Translational reset of the positioning block and bending block; (8) The positioner relies on the positioning element to fine-tune the position of the thin-walled part to ensure precise alignment; (9) The rubber pressing block is reset to press the thin-walled part tightly against the bending block; (10) Multiple sets of rubber rollers are reset to restore the clamping contact with thin-walled parts.

6. The semi-free bending-stamping composite process of thin-walled parts according to claim 1, characterized in that: The action surfaces of the left punch block and the right punch block are springback compensation surfaces.

7. The semi-free bending-stamping composite process of thin-walled parts according to claim 1, characterized in that: The rubber pressing block and the positioning element can move relative to the positioner.

8. The semi-free bending-stamping composite process of thin-walled parts according to claim 1, characterized in that: The bending block is in the shape of a circle, an ellipse, a sinusoid or a spiral.

9. The semi-free bending-stamping composite process of thin-walled parts according to claim 1, characterized in that: The side of the rubber pressing block that is in contact with the thin-walled plate is an elastic surface, and the other side is a rigid surface.

10. The semi-free bending-stamping composite process of thin-walled parts according to claim 1, characterized in that: The thin-walled part is a thin-walled plate or a thin-walled microchannel flat tube.

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